1. Field of the Invention
The present invention relates to indexing mechanisms wherein a work member is intermittently movable between a plurality of spaced dwell positions, and more specifically to apparatus for storing energy dissipated during one indexing cycle for use during a succeeding cycle.
2. Description of the Prior Art
In many manufacturing applications, there is a need to rapidly index a plurality of articles along a path of spaced work stations for a variety of work or testing functions, such as drilling, tapping, cutting, part insertion, quality checks, etc. The indexing period may be a major portion of the operation cycle. Therefore, the speed of indexing the articles between dwell periods at work stations has a great bearing on the efficiency and productivity of the machine.
Many indexing mechanisms employ rotary tables with some form of directly coupled cam-operated drive, such as the well-known Ferguson drive, to provide intermittent rotational movement to the table. The indexing speeds of such cam-operated drives cannot be readily controlled, and a new cam unit is generally required for each different angular speed vs. position profile.
To overcome these and other disadvantages, it has been suggested to drive rotary tables by means of a directly coupled servomotor. Using direct servomotor drive provides easily programmable speed vs. position profiles. However, rapid accelerations and decelerations of the rotary table require substantial armature current and resulting increases in servomotor temperature. This severly limits the servomotor performance.